A display device includes a projector, a Fresnel lens converting a projected light from the projector into a nearly parallelized light, a screen with light reflectivity on which an image by the projected light from the projector is generated, and a retrotransmissive material forming another image of an image located on one side of an element plane in a position in a space on the other side of the element plane such that the image and the other image are symmetric with respect to the element plane. The retrotransmissive material forms an image by a light that has obliquely entered the element plane, such that a position from which the light has obliquely entered the element plane and a position in which the image is formed are symmetric with respect to the element plane, and thereby forms a real image of the image on the screen.
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1. A display device comprising:
a projection device that makes a projected light exit therefrom;
a parallelizing element that converts the projected light from the projection device into a nearly parallelized light;
an image projected plane which the projected light exiting from the projection device enters via the parallelizing element, the image projected plane having light reflectivity on which an image by the projected light is formed; and
an imaging element provided between the parallelizing element and the image projected plane, the imaging element forming another image of an image located on one side of the element plane in a position in a space on the other side of the element plane such that the image and the other image are symmetric with respect to the element plane,
wherein
the imaging element makes a light which has entered the element plane almost perpendicularly from the parallelizing element travel in a straight line and forms an image by a light that has obliquely entered the element plane among diffuse lights from the image projected plane, such that a position from which the light has obliquely entered the element plane and a position in which the image is formed are symmetric with respect to the element plane, and thereby forms a real image of the image on the image projected plane.
3. The display device according to
the image projected plane is placed so as to be inclined relative to the element plane of the imaging element.
4. The display device according to
the image projected plane has, in at least part thereof, a convex portion protruding toward the element plane of the imaging element or a concave portion which is recessed as viewed from the element plane of the imaging element.
5. The display device according to
the convex portion or the concave portion has a plurality of flat surfaces which are inclined relative to the element plane of the imaging element.
6. The display device according to
the convex portion or the concave portion is curved at least in an azimuth direction.
7. The display device according to
a plurality of images obtained when an object to be displayed is viewed from different directions are projected from the projection device in such a way that the images are arranged in an azimuth direction in the convex portion or the concave portion of the image projected plane.
8. The display device according to
the imaging element is formed of a retrotransmissive material having a plurality of rectangular transmission sections that allow a light to pass therethrough, and in the retrotransmissive material, among four wall surfaces of each transmission section, at least two wall surfaces which are orthogonal to each other are reflection planes.
9. The display device according to
the arrangement of the wall surfaces among the four wall surfaces of the transmission section of the imaging element which wall surfaces among the four wall surfaces are reflection planes differs from region to region of the imaging element, and
in the imaging element, the reflection planes are disposed in such a way that each of a plurality of images projected on the image projected plane is reflected in an azimuth direction corresponding to a direction in which an object to be displayed is viewed.
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1. Technical Field
The present invention relates to display devices.
2. Related Art
A display device that includes an imaging element forming an image of an object to be projected and can generate a stereoscopic image in the air as a real image by this imaging element is disclosed in WO 07/116,639 (Patent Document 1) and JP-A-2009-229905 (Patent Document 2).
The imaging element used in the display device described in Patent Document 1 includes a plurality of unit optical elements each being formed of a dihedral corner reflector having two orthogonal mirror surfaces. This imaging element has the function of forming a real image of an object to be projected which is placed in one space of an element plane as a mirror image in a position in the other space of the element plane such that the real image and the mirror image are symmetric with respect to the element plane. As a result, when a three-dimensional object is placed in one space of the element plane, a stereoscopic image is generated in a position in the other space of the element plane such that the three-dimensional object and the stereoscopic image are symmetric with respect to the element plane.
The display device described in Patent Document 2 is configured so that the imaging element having a dihedral corner reflector similar to that of Patent Document 1 is moved above a display by a driving unit in the direction vertical to an element plane. In this display device, by changing images which are displayed on the display in synchronization with the vertical movement of the imaging element, stereoscopic midair images are generated in a space above the imaging element.
In the display device of Patent Document 1, to generate a stationary stereoscopic image, it is necessary simply to put a stationary three-dimensional object below the imaging element. However, to obtain an image of an electronically-generated dynamic three-dimensional object, a complicated structure for creating an electronically dynamic three-dimensional object by rotating a light-emitting diode (LED) array, for example, is required.
Moreover, in the display device of Patent Document 2, to allow human eyes to observe a stereoscopic image, it is necessary to move the imaging element at a frequency (for example, at a frequency of about 50 Hz or higher) at which no flicker occurs. This makes it impossible to increase the imaging element excessively, limits the size of the imaging element, and eventually limits the size of stereoscopic midair images.
Furthermore, a large-scale drive unit is required to move the imaging element at high speed in the direction vertical to the element plane.
An advantage of some aspects of the invention is to provide a display device that can generate a spatial image with a simple configuration.
An aspect of the invention is directed to a display device including: a projection device that makes a projected light exit therefrom; a parallelizing element that converts the projected light from the projection device into a nearly parallelized light; an image projected plane which the projected light exiting from the projection device enters via the parallelizing element, the image projected plane having light reflectivity on which an image by the projected light is formed; and an imaging element provided between the parallelizing element and the image projected plane, the imaging element forming another image of an image located on one side of the element plane in a position in a space on the other side of the element plane such that the image and the other image are symmetric with respect to the element plane, wherein the imaging element makes a light which has entered the element plane almost perpendicularly from the parallelizing element travel in a straight line and forms an image by a light that has obliquely entered the element plane among diffuse lights from the image projected plane, such that a position from which the light has obliquely entered the element plane and a position in which the image is formed are symmetric with respect to the element plane, and thereby forms a real image of the image on the image projected plane.
With the display device according to the aspect of the invention, the projected light exiting from the projection device enters the imaging element in a state in which the projected light is nearly parallelized by the parallelizing element. Since the imaging element has the function of making the light that has almost perpendicularly entered the element plane travel in a straight line, the projected light that has passed through the parallelizing element passes through the imaging element without change and is then projected onto the image projected plane, whereby an image is formed. At this time, since the image projected plane has light reflectivity, the projected light is reflected off the image projected plane and at the same time is diffused thereby, and enters the imaging element again in a state in which the angle distribution is widened. Since the imaging element has the function of forming an image by the light that has obliquely entered the element plane such that a position from which the light has obliquely entered the element plane and a position in which the image is formed are symmetric with respect to the element plane, a real image is generated in a space which is opposite to the side on which the image projected plane is placed with the imaging element sandwiched between them such that the real image and the image on the image projected plane are symmetric with respect to a plane. In this way, it is possible to realize a display device that can generate an image in space with a simple configuration without the need for a driving unit or the like.
In the display device according to the aspect of the invention, the image projected plane may be a flat surface.
With this configuration, by using a common screen or the like as the image projected plane, it is possible to form a planar image in space.
In the display device according to the aspect of the invention, it is preferable that, when the image projected plane is a flat surface, the image projected plane be placed so as to be inclined relative to the element plane of the imaging element.
Since an image by the light that has obliquely entered the element plane of the imaging element is formed such that a position from which the light has obliquely entered the element plane and a position in which the image is formed are symmetric with respect to the element plane, when the image projected plane is placed so as to be inclined relative to the element plane of the imaging element, a real-image forming face is also inclined, in a space which is opposite to the side on which the image projected plane is placed, such that the real-image forming face and the image projected plane are symmetric with respect to the element plane of the imaging element. Therefore, when the user looks at the real image obliquely from the direction in which the real-image forming face is inclined, the real image faces the user almost directly, whereby the user can easily view the image.
In the display device according to the aspect of the invention, the image projected plane may have, in at least part thereof, a convex portion protruding toward the element plane of the imaging element or a concave portion which is recessed as viewed from the element plane of the imaging element.
Since an image by the light that has obliquely entered the element plane of the imaging element is formed such that a position from which the light has obliquely entered the element plane and a position in which the image is formed are symmetric with respect to the element plane, when the image projected plane has a convex portion, a real-image forming face also has a convex portion protruding toward the element plane; when the image projected plane has a concave portion, the real-image forming face also has a concave portion which is recessed as viewed from the element plane. Therefore, since a real image is formed on the real-image forming face having a convex portion or a concave portion, it is possible to form a pseudo stereoscopic image.
In the display device according to the aspect of the invention, the convex portion or the concave portion may have a plurality of flat surfaces which are inclined relative to the element plane of the imaging element.
With this configuration, for example, it is possible to display a plurality of different images in accordance with the number of flat surfaces of the convex portion or the concave portion.
In the display device according to the aspect of the invention, the convex portion or the concave portion may be curved at least in an azimuth direction.
With this configuration, for example, it is possible to display a plurality of different images in accordance with the curved surface of the convex portion or the concave portion.
In the display device according to the aspect of the invention, when the image projected plane has the convex portion or the concave portion, a plurality of images obtained when an object to be displayed is viewed from different directions may be projected from the projection device in such a way that the images are arranged in an azimuth direction in the convex portion or the concave portion of the image projected plane.
With this configuration, since the plurality of images are displayed in a space opposite to the side on which the image projected plane is placed in such a way that the plurality of images are arranged in an azimuth direction, the user can view images which are different depending on the position in which the user views the image. Therefore, it is possible to obtain a pseudo stereoscopic image modified by kinematic parallax.
In the display device according to the aspect of the invention, it is preferable that the imaging element be formed of a retrotransmissive material having a plurality of rectangular transmission sections that allow a light to pass therethrough, and that, in the retrotransmissive material, among four wall surfaces of each transmission section, at least two wall surfaces which are orthogonal to each other be reflection planes.
In the “retrotransmissive material” of the aspect of the invention, among four wall surfaces of the transmission section, at least two wall surfaces which are orthogonal to each other are reflection planes, and the “retrotransmissive material” of the aspect of the invention is a so-called dihedral corner reflector. That is, when viewed from the direction vertical to the element plane, as in a common retroreflector, the light that has entered the reflection plane is reflected therefrom in the same direction as the direction in which the light has entered the reflection plane. On the other hand, when viewed from a direction which is parallel to the element plane and is vertical to the light incidence plane, as in a common reflecting mirror, the light that has entered the reflection plane is reflected therefrom at an angle of reflection which is the same as the angle of incidence. By using the retrotransmissive material of this type in the imaging element, it is possible to realize a display device with a simple configuration.
In the display device according to the aspect of the invention, it is preferable that, when the plurality of images are projected from the projection device, the arrangement of the wall surfaces among the four wall surfaces of the transmission section of the imaging element which wall surfaces among the four wall surfaces are reflection planes differ from region to region of the imaging element, and, in the imaging element, the reflection planes be disposed in such a way that each of the plurality of images projected on the image projected plane is reflected in an azimuth direction corresponding to a direction in which an object to be displayed is viewed.
With this configuration, when the user views an image from a predetermined azimuth direction, the user views only an image which is viewed from that direction and does not view an image from a different direction through the real-image forming face. As a result, a stereoscopic image by kinetic parallax looks more natural.
The invention will be described with reference to the accompanying drawings, wherein like numbers reference like elements.
Hereinafter, a first embodiment of the invention will be described by using
A display device of this embodiment is an example of a display device that can generate a planar image in space.
Incidentally, in all of the following drawings, the ratio of some component elements are sometimes changed to make the drawings more visible.
As shown in
As shown in
As shown in
In the retrotransmissive material 4 of this embodiment, as shown in
As shown in
As the screen 5, a common reflective screen which is used by being combined with a front projector can be adopted. To obtain a bright spatial image, it is preferable to use a reflective screen which has high reflectivity and can obtain a bright image. The screen 5 of this embodiment is a planar screen.
Here, by using
In
As described earlier, since the two reflection planes 9 of the retrotransmissive material 4 are orthogonal to each other, the light which has entered one reflection plane 9 is reflected off the other reflection plane 9 which is next to the one reflection plane 9 at an angle of 90 degrees. Therefore, when viewed from the direction (the Z-axis direction) orthogonal to the element plane S, as shown in
In this way, as shown in
Moreover, since the retrotransmissive material 4 has the openings 8 that penetrate the retrotransmissive material 4 in the direction vertical to the element plane S, the light that has perpendicularly entered the element plane S of the retrotransmissive material 4 travels in a straight line without entering the reflection plane 9.
In the display device 1 configured as described above, the projected light L0 that has been made to exit from the projector 2 enters the retrotransmissive material 4 vertically from above in a state in which the projected light L0 is nearly parallelized by the Fresnel lens 3. Since the retrotransmissive material 4 has the function of making the light that has almost perpendicularly entered the element plane S travel in a straight line, the light L1 parallelized by the Fresnel lens 3 passes through the retrotransmissive material 4 without change and is then projected onto the screen 5, whereby an image is formed thereon. Incidentally, since the projected light is blocked in an area other than the openings 8 of the retrotransmissive material 4, the smaller the numerical aperture, the darker the image on the screen 5. Therefore, by increasing the numerical aperture by minimizing the spacing between the openings 8 which are next to each other, it is possible to make the image on the screen 5 bright to some extent without major loss of image quality.
At this time, since the screen 5 is a reflective screen, the projected light is reflected off the screen 5 and at the same time is diffused in accordance with the scattering characteristics of the screen 5, and enters the retrotransmissive material 4 again vertically from below in a state in which the angular distribution is widened. As described earlier, the retrotransmissive material 4 has the function of forming an image by the light that has obliquely entered the element plane S such that a position from which the light has obliquely entered the element plane S and a position in which the image is formed are symmetric with respect to the element plane S. Therefore, a real image is generated in a space which is opposite to the side on which the screen 5 is placed with the retrotransmissive material 4 sandwiched between them such that the real image and the image on the image projected plane are symmetric with respect to a plane.
That is, in this embodiment, as shown in
Therefore, as shown in
In an example shown in
As described above, with the display device 1 of this embodiment, it is possible to realize a display device that can generate an image in space with a simple configuration without the need for a driving unit or the like.
Specifically, by only placing the screen 5 below the retrotransmissive material 4 and projecting an image onto the screen 5 from the projector 2 via the Fresnel lens 3, it is possible to generate a spatial image. Thus, there is no need to place a complicated apparatus or the like below the screen 5. As a result, even when the retrotransmissive material 4 is incorporated into a desk, for example, since there is no cumbersome apparatus or the like under the desk, the observer K can put chairs around the desk and sit the chair in such a way as to place his/her legs under the desk. Therefore, a plurality of observers K are allowed to view a real image in their respective positions close to one another. Moreover, since a configuration in which the projector 2 and the Fresnel lens 3 are placed on the ceiling, for example, can be adopted, when the display device 1 is not used, it is possible to move easily the desk into which the retrotransmissive material 4 is incorporated. In this way, it is possible to provide an easy-to-use display device.
Incidentally, in this embodiment, a configuration in which the retrotransmissive material has rectangular openings has been taken as an example. However, in place of openings, a transmission section that allows the light to pass therethrough may be adopted. That is, a configuration may be adopted in which, on a plate material made of a transparent material, a reflector is placed in a grid-like pattern or so as to have the shape obtained by removing a part of a grid.
Hereinafter, a second embodiment of the invention will be described by using
A display device of this embodiment is an example of a display device that can generate a pseudo stereoscopic image in space.
As shown in
While the screen 5 of the first embodiment has a planar shape, the screen 13 of this embodiment has, as shown in
In this embodiment, as shown in
In
In this embodiment, it is preferable that the retrotransmissive material 12 have a configuration shown in
In the retrotransmissive material 4 of the first embodiment, as shown in
When the retrotransmissive material 12 has the above-described configuration, the lights from the images G1 to G4 projected on the four image projected planes of the screen 13 are reflected by the retrotransmissive material 12 to only the sides on which the images are located. That is, by the retrotransmissive material 12, the light from the image G1 shown in
Also in this embodiment, it is possible to obtain the same effects as those of the first embodiment, such as realizing a display device that can generate an image in space with a simple configuration.
In this embodiment, in particular, since the screen 13 has a three-dimensional shape, the real-image forming face J also has a three-dimensional shape, making it possible to give a three-dimensional appearance to a spatial image formed thereon. Furthermore, in the display device 11 of this embodiment, since different four spatial images can be generated, the observer K can observe spatial images viewed from points of view which are different from one another by 90 degrees when the observer K views the spatial images while moving around the display device 11. Therefore, it is possible to obtain a pseudo stereoscopic image modified by kinematic parallax.
Incidentally, in this embodiment, a case in which the screen 13 has the shape of a quadrangular pyramid has been described. However, the screen 13 may have the shape of a polygonal pyramid, such as a triangular pyramid, other than a quadrangular pyramid. Moreover, a screen having two image projected planes obtained by folding a planar screen once may be used. In these configurations, which inner wall surface of the opening of the retrotransmissive material serves as a reflection plane may be appropriately determined in accordance with the shape of the screen.
In addition, in this embodiment, a configuration in which the retrotransmissive material has rectangular openings has been taken as an example. However, in place of openings, a transmission section that allows the light to pass therethrough may be adopted. That is, a configuration may be adopted in which, on a plate material made of a transparent material, a reflector is placed in a grid-like pattern or so as to have the shape obtained by removing a part of a grid.
Hereinafter, a third embodiment of the invention will be described by using
As is the case with the second embodiment, a display device of this embodiment is a display device that can generate a pseudo stereoscopic image in space. However, the configuration of a retrotransmissive material, the shape of a screen, and an image which is projected thereon are different from those of the second embodiment.
In this embodiment, as shown in
In
In this embodiment, it is preferable that the retrotransmissive material 15 have a configuration shown in
By using such a retrotransmissive material 15, also in this embodiment, as is the case with the second embodiment, the lights from the images G1 to G8 projected on the screen 16 are reflected by the retrotransmissive material 15 to only the sides on which the images are located. By the action described above, only the real image in the direction in which the observer K is located is observed by the observer K. On the other hand, the light from an image located in a direction other than the direction in which the observer K is located is not reflected in the direction in which the observer K is located. Thus, the observer K views only a real image located in front of the observer K and does not view a real image on the back side of the real-image forming face through the real-image forming face.
The observation range can be set by the reflection characteristics of the screen 16. For example, to narrow the observation range, the angle distribution of the light reflected off the screen 16 is narrowed; to widen the observation range, the angle distribution of the light reflected off the screen 16 is widened. The observation range is appropriately set in accordance with the contents to be displayed.
Also in this embodiment, it is possible to obtain the same effects as those of the first and second embodiments, such as realizing a display device that can generate an image in space with a simple configuration. Moreover, as is the case with the second embodiment, by providing a real-image forming face with a three-dimensional shape, it is possible to give a three-dimensional appearance to a spatial image.
Incidentally, in this embodiment, as an example of an image which is projected onto the screen 16, as shown in
Furthermore, by making settings so as to make the right and left eyes view different spatial images by narrowing the reflection characteristics of the screen 16, it is possible to display a stereoscopic image using binocular parallax. As described above, since the observer is allowed to observe a spatial image in accordance with a position in which the observer views the image, it is possible to obtain a natural stereoscopic image.
Moreover, a plurality of images which are projected onto the screen 16 can be generated by obtaining continuous images by a method such as taking images of the object to be displayed T while rotating the object to be displayed T or taking images of the object to be displayed T while making an observation point move equidistantly and at the same angle, and performing image conversion on the images thus obtained. Furthermore, the plurality of images which are projected onto the screen 16 can also be obtained by placing a mirror corresponding to the shape of the screen 16 on the same axis as the optical axis of a shooting lens and taking images with the optical axis set in a vertical direction.
In this embodiment, an example in which the screen 16 has a conical shape has been described. However, the screen 16 may have an elliptic conical shape or other pyramidal or conical shapes. Moreover, the cross-sectional shape of the screen at a plane vertical to the image projected plane may be a curve. That is, the screen may have the shape of a hemisphere, for example. The placement of the openings of the retrotransmissive material and the placement of the reflection planes in these configurations are appropriately determined in accordance with the shape of the screen.
Moreover, in the second and third embodiments, examples in which the screen has a shape protruding downward have been described. However, the screen may have a shape protruding upward toward the retrotransmissive material. In such a case, the real-image forming face has a shape protruding downward toward the retrotransmissive material. Furthermore, in place of forming the screen in such a way that the entire screen is recessed upward or downward, a convex portion or a concave portion may be formed in only part of the screen.
It is to be understood that the technical scope of the invention is not limited to the embodiments described above and various changes can be made therein without departing from the spirit of the invention. For example, in the embodiments described above, a retrotransmissive material having a plurality of rectangular openings has been taken as an example of an imaging element. However, the imaging element is not limited to the retrotransmissive material of this type, and other imaging elements may be used as long as they have optical characteristics shown in
The entire disclosure of Japanese Patent Application No. 2011-055184, filed Mar. 14, 2011 is expressly incorporated by reference herein.
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